1. Field of the Invention
The present invention relates to an apparatus for intermitted feeding of strip shaped blank to a punch press which is equipped with tools adapted for intermittent working of the strip shaped blank, which feeding apparatus includes a housing and a threaded spindle housing arranged on said housing, an upper shaft assembly and an upper feeding roller mounted on said upper shaft assembly, a lower shaft assembly and a lower feeding roller mounted on said lower shaft assembly, which feeding rollers are adapted to grip said blank to be fed by clamping the blank at both its sides and to feed the blank intermittently by an intermittent rotational movement, of which shaft assemblies at least one is drivingly connected to a an intermittently operating electric servomotor and the upper shaft assembly is supported in a rocker which is pivotally mounted at said housing through a rocker shaft, by means of which rocker said upper shaft assembly is moveable towards and away from said lower shaft assembly.
The invention relates further to a method of operating said feeding apparatus, which feeding apparatus includes further a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and comprises a press control apparatus which communicates with the control apparatus of the feeding apparatus and comprises further a rod having an elongate hole and which is moveable between a top dead center position and a bottom dead center position, and having a bolt extending through the elongate hole, whereby in order to insert a fresh strip shaped blank between the upper feeding roller and the lower feeding roller the upper feeding roller is moved into a high lift position in order to set a predetermined distance between the upper feeding roller and the lower feeding roller.
The invention relates further to the method of operating the feeding apparatus, which feeding apparatus comprises a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and which comprises a press control apparatus which communicates with the control apparatus of the feeding apparatus and comprises further a rod which is movable between a top dead center position and a bottom dead center position, which rod has an elongate hole having a upper and a lower end whereby the first arm of the first double arm lever unit engages the rod by a bolt extending through the elongate hole.
The invention relates also to a method of operating the feeding apparatus as set forth above, which feeding apparatus has a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and which has a press control apparatus which communicates with the control apparatus of the feeding apparatus, and has further a rod which is moveable between a top dead center position and a bottom dead center position, which rod has an elongate hole having a upper and a lower end, whereby the first arm of the first double arm lever unit engages the rod by a bolt extending through the elongate hole.
The invention relates also to a method of operating the feeding apparatus set forth above, wherein the feeding apparatus comprises a control apparatus and cooperates with a press which has a moveable upper tool and a stationary lower tool, which upper tool is mounted to a punch which is moveable between a top dead center position and a bottom dead center position, and which comprises a press control apparatus which communicates with the control apparatus of the feeding apparatus, and comprises further a rod which is moveable between a top dead center position and a bottom dead center position, which rod has an elongate hole having a upper and a lower end, whereby the first arm of the first double arm lever unit engages the rod by a bolt extending through the elongate hole which punch is driven by a rotating drive and the eccentric disc of the rod is driven by a drive motor, which upper tool has positioning pins for a precise positioning of the strip shaped blank in the press during the working of same, which positioning pins are moved into pre-punched positioning holes in the strip shaped blank and which positioning pins include a conical head portion, which upper feeding roller is moved away from the bottom feeding roller as soon as the conical head portions are moved partly into the positioning holes and thereafter set again onto the strip shaped blank as soon as the conical head portions have been lifted partly out of the positioning holes.
2. Description of the Prior Art
The punch presses referred to herein are especially high speed presses with stroke numbers up to 2000 strokes per minute. These presses are equipped with tools for a working of a (or several) fed strip shaped blank(s), whereby punching operations, embossing operations, bending operations, a riveting, a producing of threads, etc. are performed.
The movement of the strip shaped blank which is processed in the press proceeds, thereby, intermittently, thus step by step. During a working step, e.g. a punching, quite obviously no feeding movement of the strip shaped blank occurs. It is often positioned precisely, thus arrested by positioning pins located in the tools. After the termination of the processing step, for instance after a punching tool has been moved out of the hole which has been punched through, the strip shaped blank is fed forwards by a set distance and is again stopped, so that the next subsequent processing step can be performed.
The feeding or advancing, resp. movement of the strip shaped blank is accomplished by a (or several, located at the entry and the exit of the press) feeding or forwarding, resp. apparatus (or apparatuses, resp.) in order to draw the strip shaped intermittently off a storage spool and feed same intermittently to the press.
These feeding apparatuses comprise conventionally feeding members in order to feed and forward the strip shaped blank. It is, thereby, clamped and moved forward by the feeding members. When the feeding members return into their initial, that is starting position, the clamping is released. Additionally, the clamping is temporarily released during the time span, during which the tools perform a processing or working, resp. step of the strip shaped blank, specifically in case of positioning pins.
Designs of such feeding apparatuses have become known, in which the clamping members are designed as linearly moving clamping tongues. Other designs comprise oscillating segment rollers which perform rotational movements.
Furthermore, feeding apparatuses with electrical servomotors have become known. A first servomotor is, thereby, allocated to the feeding operation of the clamping members and a further, second electric servomotor is allocated to the intermittent lifting of a clamping member off the strip shaped blank. Such servomotors are produced and sold by several companies. The operation of these servomotors is electronically controlled. These new feeding apparatuses comprise feeding members in form of completely cylinder shaped feeding rollers mounted on shafts which rotate intermittently always in the same sense of rotation. Of these feeding rollers one is supported in a structural member which is drivingly connected to the further servomotor, based on the operation of which this feeding roller is moved against the strip shaped blank for a clamping of same and away from this member for a releasing of same.
Due to the presently extremely high number of strokes, the masses of the moving parts of a feeding apparatus have a large impact due to the forces of inertia and the moments of inertia, and have, furthermore, a large influence regarding the precision of the produced product. Furthermore, due to the time spans for the acceleration and deceleration of movements, the arrangement and design of the moving parts must be selected in such a manner, that an operation of a high number of strokes can be performed safely.